Various digital communication networks exist worldwide and provide various services for registered user devices. In many areas different networks overlap and service to more than one network is possible.
Multi-mode devices have been proposed which are able select and register with one from a number of networks, depending on the availability of the networks in question.
A problem with this arrangement is that a multi-mode device having a single transmitter/receiver would not be able co-establish and co-register on two networks simultaneously without losing data. Therefore an already established call on one network must be terminated before the device can switch to the other network, i.e. the call must be relinquished.
It would be possible to build a device with two receivers, so as to monitor and receive from two networks simultaneously, thus preserving an established call and switching it from one network to another. However, a device with two receivers would be expensive and significantly larger in size than a single receiver terminal. Similarly it would be possible to provide two transmitters for maintaining a call on one network and establishing a call on the second network during a handover period before dropping the call on the first network. This too would be expensive.
This invention seeks to provide a radio communications device and method in which the above mentioned disadvantages are mitigated.